Sterilization and disinfection
From IDWiki
Background
Definitions
- Cleaning is the process of removing soil and organic material, usually with water and detergents or enzymes
- Sterilization is a process that eliminates all forms of microbial life
- Disinfection is a process that eliminates many or all pathogenic microbes on inanimate objects, with the exception of spores
- Chemical sterilants are disinfectants that will kill spores with prolonged exposure (2 to 12 hours)
- High-level disinfectants will kill all microorganisms except large numbers of bacterial spores within a shorter amount of time (e.g. 20 minutes)
- Low-level disinfectants will kill most vegetative bacteria, some fungi, and some viruses within a short amount of time (e.g. 10 minutes)
- Intermediate-level disinfectants may be cidal for mycobacteria, vegetative bacteria, most viruses, and most fungi, but are not sporicidal
Sterilization
- The process of sterilization destroys all forms of microbial life
- May be physical or chemical methods
- Steam under pressure
- Dry heat
- EtO gas
- Hydrogen peroxide gas plasma
- Liquid chemicals
- Equipment must be cleaned first, before attempting to disinfect or sterilize it
Spaulding Classification of Medical Equipment
| Classification | Contact with | Processing | Examples |
|---|---|---|---|
| Critical | Sterile tissue or vascular system | Cleaning followed by sterilization | Surgical instruments, biopsy instruments, and foot care equipment |
| Semi-critical | Non-intact skin or mucous memranes, but not penetrating the skin | Cleaning followed by a minimum high level disinfection | Respiratory equipment, flexible endoscopes |
| Non-critical | Intact skin | Cleaning followed by low level disinfection | Tourniquets, BP cuffs, linen, and furniture |
Rutala Modification
- Endoscopes, which secondarily enter sterile tissues, should be considered critical
Methods of Sterilization and Disinfection
| Method | Corrodes Metal | Smooth, Hard Surfaces | Rubber Tubing and Catheters | Polyethylene Tubing and Catheters | Lensed Instruments | Thermometers | Hinged Instruments | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| S | HLD | ILD | LLD | S | HLD | S | HLD | S | HLD | LLD | S | HLD | ||
| Heat sterilization, including steam or hot air for 3 to 30 min | X | X | X | X | X | |||||||||
| Ethylene oxide gas for 1 to 6 hours | X | X | X | X | X | |||||||||
| Hydrogen peroxide gas plasma for 45 to 72 minutes | X | X | X | X | X | |||||||||
| Glutaraldehyde-based formulations (>2% gluteraldehyde) or gluteraldehyde 1.12% and phenol/phenate 1.93% | 10 h | X | 10 h | X | 10 h | X | 10 h | X | 10 h | X | ||||
| Hydrogen peroxide 7.5% | X | 6 h | X | 6 h | X | 6 h | X | 6 h | X | 6 h | X | |||
| Peracetic acid >0.2% for 12 min at 50 to 56ºC | X | X | X | X | X | |||||||||
| Hydrogen peroxide 7.35% and peracetic acid 0.23%, or hydrogen peroxide 1% and peracetic acid 0.08% | X | 3 to 8 h | X | 3 to 8 h | X | X | X | 3 to 8 h | X | X | X | |||
| Ortho-phthalaldehyde (OPA) 0.55% | X | X | X | X | X | |||||||||
| Wet pasteurization (30 min at 70ºC) with detergent cleaning | X | X | X | X | ||||||||||
| Hypochlorite generated by electrolyzing saline | X | X | X | X | X | X | ||||||||
| Ethyl or isopropyl alcohol 70 to 90% | X | X | X | |||||||||||
| Sodium hypochlorite 5.25 to 6.15% (diluted household bleach) | X | X | ||||||||||||
| Phenolic germicidal detergent solution | X | X | ||||||||||||
| Iodophor germicidal detergent solution | X | X | ||||||||||||
| Quaternary ammonium germicidal detergent solution | X | |||||||||||||
- Exposure times:
- Sterilization: varies by method
- High-level disinfection: 12 to 30 minutes at ≥20ºC
- Intermediate disinfection: ≥1 min
- Low-level disinfection: ≥1 min
Medical Device Reprocessing Department (MDRD)
- Needs separate areas for receiving soiled instruments, decontaminating, cleaning, sterilizing, and storing
- Treated essentially like an OR, with controlled temperature and humidity, with dedicated ventilation system
- Negative pressure in decontamination areas and positive pressure in clean areas
Pre-Cleaning
- Dismantle and sort devices, then soak them
Cleaning
- Remove all visible soil from every accessible surface
- Can use ultrasonic machines and washing machines
- Rinse to remove detergents, then dry
Sterilization
- High temperature sterilization whenever possible
- Low-temperature sterilization can be done for heat sensitive critical and semi-critical items
- Uses gas, including hydrogen peroxide gas plasma or vapour, or ozone (but that needs 4 hours)
- Needed for things with plastic, for example
- Liquid emersion can be done for heat sensitive crticical and semi-critical items
- Hydrogen peroxide most common liquid
Monitoring
- Spore tests: compare a strip that went through the autoclav to a control that was held outside
- ATP system test strips
Storage
- Equipment must be stored until results are available from the spore test for that batch
- Controlled temperature and humidity
